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 Posted: Oct 11, 2019 12:44AM
TK
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AU
+1 Just fitted my super dooper stainless LCBs. The flange holes were no way going on the head without a hell of a lot of filing. Thanks suppliers!

 Posted: Oct 10, 2019 01:02PM
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Those headers always split along the weld. Best way of repairing them is to braze the crack not weld it - lower temperature, and braze is more flexible. Once it is brazed it will not crack again. And yes, always do it with the header bolted on the head to avoid warping. 

 Posted: Oct 6, 2019 07:00AM
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US
Quote:
Originally Posted by workinprogress
Also when welded, may not have been in correct place. When I have welded splits I always bolt to head then weld to help keep shape

+1

If you just enlarge the flange holes, the manifold pipes won't necessarily line up with the ports in the head.  Use the head as the fixture and then a BFH to tweak things (if necessary) after welding.

Doug L.
 Posted: Oct 6, 2019 06:23AM
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CA
Also when welded, may not have been in correct place. When I have welded splits I always bolt to head then weld to help keep shape. 

 Posted: Oct 6, 2019 02:48AM
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GB

Perfectly normal on any tubular manifold, including the factory 3-branch ones - they ALL close up and will eventually crack. 

If you wrap the pipes it makes any cracking worse as the trapped heat embrittles the steel through carbon scavenging.

Even OEM cast iron manifolds will close up if used hard in anger - the MPi and Metro/Cooper ones pull in quite happily and need the outer holes elongating.

 Posted: Oct 5, 2019 07:47PM
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I'm getting pretty annoyed by the sloppy craftsmanship of aftermarket parts—expensive aftermarket parts at that. The latest rub came when I attempted to refit my Maniflow headers after doing a head gasket job. When I removed the headers I noticed a good-sized split in the weld where the 2-into-1 tubes meet. I figured the weld just gave up after repeated heat cycles and vibration. I had them re-welded and when I went to refit them, I discovered 3 of the stud holes in the headers were offset a ¼” from the studs in the cylinder head!


Thinking the re-weld job changed the shape of the headers, I noted the new exhaust gasket lines up fine with the head studs. I suspect that the shop that built my engine simply applied muscle and perhaps a BFH to get the headers to fit, breaking the weld. So now I'm having to file and drill the header holes to get them to align with the cylinder studs, all the while cursing Maniflow and the shop that did the original build. I always wondered by my eyes stung whenever I worked on the engine while it was running.

 

Michael, Santa Barbara, CA

. . . the sled, not the flower

      Poser MotorSports